ABSTRACT
ABSTRACT: Several previous studies have demonstrated the merits of using Carbon Reinforced Plastic (FRP) composites for strengthening existing reinforced and prestressed concrete bridges. These studies have also shown that the success of this strengthening technique is highly dependent on the effectiveness of the bond between the concrete and the FRP.Yet, current available or proposed design specifications do not provide standard experimental methods to characterize the properties of the bond nor do they provide simple and accurate methods to analyze the bond’s effectiveness when FRP sheets are attached to beams subjected to transverse and bending loads. In this paper, the authors propose an experimental set up to perform a laboratory investigation of the behavior of the interfacial bond between concrete and FRP sheets. This procedure leads to the characterization of the nonlinear behavior of the bond through the development of a material law for the FRPconcrete interface appropriate for the corresponding adherents material properties. The nonlinear material law of the FRP-concrete interface, which considers the shear-debonding mode of failure, can then be incorporated into a finite element numerical model for predicting the load response of FRP-strengthened beams while accounting for the initiation of debonding and the subsequent propagation of the bond’s fracture along the interface between the FRP and the concrete substrate as well as other possible failure modes such as concrete crushing and FRP rupture. The validity of the numerical model is verified by comparisons to experimental results of externally strengthened reinforced concrete structures.
